A significant challenge facing testing laboratories is quality control. Some reports have indicated that mutations in cancer genes were correctly identified by only 70% of testing laboratories (Bellon, et al. External Quality Assessment for KRAS Testing Is Needed: Setup of a European Program and Report of the First Joined Regional Quality Assessment Rounds. Oncologist. 2011 April; 16(4): 467-478). Questions have been raised regarding how to monitor next generation sequencing and assays as well as the concordance of variant calls across multiple platforms, library preparation methods, and bioinformatic pipelines. Compositions and methods providing a flexible, single reagent representing a large number of genetic variants are desired by those of ordinary skill in the art and are described herein.